Lean, mean but decidedly green, my young friends were determined to rid their garden of tomato hornworms by picking them off rather than spraying them. “We killed the mothers!”, they exclaimed in triumph, and told how they’d sought out the fat green worms with rows of small white eggs on their backs.
Unknowingly, they had destroyed their best allies. Those eggs were laid not by the hornworms but by the parastic braconid wasp whose larvae would have fed on their hosts once they’d hatched.
No one expects even a seasoned gardener to be an entymologist, but we’re all learning lots more about the complex lives of insects in the garden. Most people know that while some are pests that bite, eat plants or spread disease, others play helpful roles. Insects such as bees, butterflies and hover flies are important pollinators.
Others such as ladybird beetles and lacewings are hungry consumers of aphids and other plant-nibblers. Dragonflies feast on mosquitoes. Encarsia wasps eat whiteflies. Ant lions pursue ants. Ground beetles love cutworms. It’s a Salvation Army of aptly named troops — the spined soldier bug, the assassin bug, the minute pirate bug, the insidious flower bug, the robber fly.
Still, I’ve never liked the concept of good bugs vs. bad ones. “Beneficial insect” is a slightly better term, since such creatures do confer benefits on us, but some voracious ones eat good guys and bad guys alike.
And not many of us can tell the difference between good thrips and bad ones, good and bad mites, good and bad nematodes. They don’t wear white or black hats. Besides, even the so-called bad ones are essential. When their numbers dwindle, the helpful predators they feed decline too.
Giving garden plants a rich organic soil, enough water and whatever else they need to thrive will leave them less vulnerable to pests. It’s also important to encourage insect diversity in and around the garden.
Supply nectar-rich flowers such as butterfly weed, goldenrod, daisies and asters. Use flowering cover crops such as buckwheat and clover. Plant flowering herbs such as dill, mint, thyme and lavender. Creating a diverse environment is much more effective than buying and releasing predators.
Above all, avoid poison dusts and sprays. It’s fine to squish individual cutworms, or dislodge aphids with a water hose. But to release poison (which insects often grow resistant to anyway) is to throw a bomb into the animal-plant marketplace and bring its intricate commerce to a crashing halt.